The long term objective of this application is to elucidate the molecular mechanisms by which nitric oxide synthase I (NOS1) gene expression is modulated in the central and peripheral nervous systems in response to methamphetamine-induced, ischemic, and traumatic injury, respectively. Specifically, we hope to identify and characterize cis elements that regulate transcription of the human NOS1 gene, and to identify factors and signal transduction pathways that act vis a vis these elements to induce NOS1 in response to these types of injuries. NOS1 is a complex gene with at least three distinct promoter complexes regulating transcription in the CNS. Specific aim 1 proposes to identify cis elements that are important for CNS-specific expression of the NOS1 promoters. These studies utilize retroviruses that express an EGFP reporter under transcriptional control by individual human NOS1 promoters and cell culture as well as in vivo assay systems. Specific aim 2 proposes to determine whether individual human NOS1 promoters are activated in response to methamphetamine treatment, ischemia, and peripheral nerve injury, respectively. In these studies, lines of transgenic mice expressing different NOS1-lac Z fusion genes will be subjected to the each of the three neuronal injury models, followed by analysis of fusion gene expression. Specific aim 3 proposes to determine whether these fusion genes are activated in cortical neuronal cultures by treatments producing excitotoxicity and by modulation of signaling pathways. Expression of nitric oxide (NO) is correlated with neuroprotection in neurodegenerative disease and, depending on cellular context, NO also acts as a potent neurotoxin. Indeed, NO toxicity is a major cause of neuronal cell death during stroke. Consequently, it is critical to understand all processes that contribute to the formation of NOS in the CNS. By focusing on transcriptional control of human NOS 1, this application has great potentia1 significance in the context of new drug discovery and in providing a more profound understanding of the plasticity of gene expression in the CNS.